If x is the square of the number when $$\left(\frac{2}{5} \text{of}  6\frac{1}{4} \div \frac{3}{7}\right)$$ of $$1 \frac{2}{7}$$ is divided by $$11\frac{1}{4}$$, then the value of 81x is:

Given,

$$x=\left(\frac{\left(\frac{2}{5}\text{of}  6\frac{1}{4}\div\frac{3}{7}\right)\text{of}  1\frac{2}{7}}{11\frac{1}{4}}\right)^2$$

$$x=\left(\frac{\left(\frac{2}{5}\text{of}  \frac{25}{4}\div\frac{3}{7}\right)\text{of}  \frac{9}{7}}{\frac{45}{4}}\right)^2$$

$$x=\left(\frac{\left(\frac{5}{2}\div\frac{3}{7}\right)\text{of}  \frac{9}{7}}{\frac{45}{4}}\right)^2$$

$$x=\left(\frac{\left(\frac{5}{2}\times\frac{7}{3}\right)\text{of}  \frac{9}{7}}{\frac{45}{4}}\right)^2$$

$$x=\left(\frac{\frac{35}{6}\text{of}  \frac{9}{7}}{\frac{45}{4}}\right)^2$$

$$x=\left(\frac{\frac{35}{6}\times\frac{9}{7}}{\frac{45}{4}}\right)^2$$

$$x=\left(\frac{\frac{15}{2}}{\frac{45}{4}}\right)^2$$

$$x=\left(\frac{2}{3}\right)^2$$

$$x=\frac{4}{9}$$

$$\therefore\ 81x=81\times\frac{4}{9}=36$$

Hence, the correct answer is Option C